1. Field of the Invention
The present invention relates to an absorbent article suitable for absorbing menstrual blood and so on discharged from the female genital organ, more particularly, relates to an absorbent article having flexible hinges that can be deformed to bring a central portion having an absorbent layer into close contact with the wearer's excretory part.
2. Related Art
Absorbent articles intended to absorb menstrual blood discharged from a female genital organ are typically constructed to include an absorbent layer, a liquid-permeable topsheet covering the skin surface of the absorbent layer, and a liquid-impermeable backsheet covering the garment surface of the absorbent layer. Generally, they are worn with the backsheet adhered to an inner side of a groin piece of an undergarment through a pressure-sensitive adhesive layer.
In order to certainly collect liquid discharged from an excretory part of a wearer by the absorbent article, the skin surface is preferably brought into close contact with the wearer's excretory part. If a clearance is caused between the skin surface of the absorbent article and the excretory part when the absorbent article is worn in the crotch, discharged liquid applied to the topsheet may flow along the topsheet to easily cause leakage laterally of the absorbent article or leakage toward the wearer's buttocks, which results in fouling the undergarment or other garments.
Particularly when the absorbent article is fixed to a groin piece of an undergarment and worn in the wearer's crotch, motion of the wearer's body easily causes displacement of the undergarment with respect to the wearer's crotch. Furthermore, when the absorbent article held between the thighs together with the groin piece of the undergarment is laterally compressed, the absorbent layer is easily laterally deformed by compression, so that a clearance is easily caused between the skin surface of the absorbent article and the wearer's excretory part, as set forth above.
Accordingly, there has been developed a technology aiming at bringing the central portion of the absorbent article into close contact with the wearer's excretory part, as disclosed in the following Patent Publications 1 and 2.
Patent Publication 1 discloses an absorbent article, in which a raised portion where an absorbent body is of an increased thickness is provided centrally while a pair of curved top-side grooves is formed on right and left sides of the raised portion. The top-side grooves can serve as flexible hinges to facilitate folding of the absorbent body, which aims at deforming the raised portion to have an arc cross-section projecting toward the wearer.
Patent Publication 2 discloses a sanitary napkin, in which an upper surface is provided, at both sides thereof, with compressed grooves extending longitudinally to approach each other at a central portion, and a lower surface is provided, at a width direction center thereof, with a compressed groove extending longitudinally to the vicinity of a rear end. When the wearer's thighs exert a stress on it, therefore, the portion extending along the compressed groove formed in the lower surface is lifted up so that the sanitary napkin can be deformed to have a W-shaped cross section, coming into suitable contact with a female private part.
[Patent Publication 1]
Japanese Unexamined Patent Publication No. 10-328232
[Patent Publication 2]
Japanese Examined Utility-Model Publication No. 5-39691
When the absorbent article disclosed in Patent Publication 1 is subjected to a compressive force, however, since the absorbent body is so bent that its skin surface forms valleys at the top-side grooves which are disposed one on each side, the raised portion between the top-side grooves tends to deform away from the wearer's skin, thereby reducing the degree of close fitting between the raised portion and the wearer's excretory part.
In addition, since the absorbent body provided in the raised portion is generally of a low density and soft so that a soft feel can be given to the wearer's crotch, the absorbent article subjected to a lateral pressure tends to cause a mere lateral compression of the raised portion rather than bending of the absorbent body at the top-side grooves. Furthermore, since the resiliency of the absorbent body decreases when discharged liquid is given to the absorbent article in such a deformed state, the absorbent body cannot be so restored as to spread from the laterally compressed state. Therefore, the area of the skin surface of the absorbent article is substantially decreased, so that discharged liquid cannot be sufficiently collected by the absorbent article.
In the sanitary napkin disclosed in Patent Publication 2, on the other hand, providing the compressed groove centrally of the back surface aims at deforming the absorbent layer to project toward the wearer's skin. However, since a soft, low-density material is used for the absorbent layer, as set forth above, its strength decreases after absorption of discharged liquid, so that the absorbent layer is easily crushed from the projecting state. As a result, it becomes difficult to keep the absorbent layer in suitable contact with the wearer's excretory part. If a high-density material is used for the absorbent layer so as to maintain the projecting state even after absorption of discharged liquid, on the other hand, a stiff feel will be given disadvantageously to the wearer's crotch.
In addition, the density of the absorbent layer is increased to have a high stiffness at the portion extending along the compressed groove formed in the back side of the sanitary napkin. Since the compressed groove is located at the mountain top when the absorbent layer is deformed in the projecting state, the portion of the compressed groove also tends to give a stiff feel to the wearer's body.
It should also be noted that the absorbent article disclosed in Patent Publication 1 is elongated and the raised portion rising from the skin surface is also elongated. However, the top-side grooves that can function as the flexible hinges are provided only on both sides of the front portion of the raised portion, without providing means for bringing the rear portion of the raised portion into close contact with the wearer's body. Therefore, it is difficult to bring the rear portion of the raised portion into dose contact with the area from the crotch to the buttocks, particularly, the perineum of a female (i.e., the area between the posterior part of the vaginal opening and the anus).
Accordingly, menstrual blood discharged from the vaginal opening is liable to leak toward the buttocks during both nighttime and daytime.